Starting and operating circuit for a discharge device



May 29, 1962 l.. l.. GENulT ETAL STARTING AND OPERATING CIRCUIT FOR ADISCHARGE DEVICE 2 Sheets-Sheet 1 Filed Nov. 13, 1959 M M f. M M M m May29, 1952 L. L.. GENUIT ETAI.

STARTING AND OPERATING CIRCUIT FOR A DISCHARGE DEVICE Filed NOV. 13,1959 2 Sheets-Shea?l 2 INE Vol 7S 3,031,147 Patented May 29, 19623,037,147 STARTHNG AND GPERATHNG CHRCUT FR A UISCHARGE DEVCE Luther L.Genuit, Danvilie, Ill., and Sohn Popa, Lyndburst, Va., assignors toGeneral Electric Company, a corporation of New Yori;

Filed Nov. 13, 1959, Ser. No. 352,67@ 9 Claims. (Cl. S15-05) rThisinvention relates to circuits for starting and operating arc dischargedevices on direct current from an alternating current source.

ln providing a direct current supply to arc discharge devices, such asmercury vapor lamps, it is desirable that the direct current poweroutput at the lamp terminals be substantially stable irrespective of theusual variations in the voltage and frequency of the alternating currentsupply. Such a requirement must be met in applications where a lightsource of substantially constant luminous intensity is to be employed,as for example, in a data processingr machine for counting and sortingpunched data cards and where an alternating current supply is to be usedas the power source.

An exemplary circuit of the prior art is described and claimed in US.Patent No. 2,892,126 granted lune 23, i959, in the name of lohn Popa andassigned to the same assignee. A voltage multiplying and filter circuitis used in conjunction with a full-wave rectifier and anV auto-1transformer to start and operate a discharge device. Although thiscircuit was generally satisfactory in its operation, it was found thatslight fluctuations occurred in the luminous intensity of the dischargedevice as the voltage and frequency of the alternating supply werevaried. This invention provides an improved circuit which utilizes astabilized power transformer apparatus and a voltage multiplying andfilter circuit which function as an oscillatory circuit during thestarting condition and during the operating condition of the circuit asa filter circuit.

in a circuit used to furnish direct current to an arc discharge deviceemployed as a constant light source it is important that the lamp startsreliably and operates at a substantially constant level of luminousintensity within the range of normal variations in line frequency andvoltage. In addition, it is desirable that such circuits be readilyadaptable to automatic starting, that the capacitors used in the circuitbe of relatively small size and that the need for separate startingwindings in the alternating current transformer used in the circuit beeliminated. Adaptability to automatic starting is a desirable featuresince it results in convenience to the operator. A reduction incapacitor size and the number of transformer windings is an advantageousfeature since it results in reduction in the manufacturing costs.

Accordingly, a general object of the present invention is to provide animproved circuit for starting and operating an arc discharge ldevice ondirect current from an alternating current supply.

A more specific object of the invention is to provide an improvedcircuit that will star-t and operate an arc discharge device on directcurrent from an alternating current source and furnish a substantiallyconstant direct current power supply at the terminals of the arcdischarge device irrespective of normal fluctuations in the alternatingcurrent power supply voltage and frequency.

Another object of the invention is to provide an improved circuit thatwill reliably start an arc discharge device on direct current from analternating current supply.

A further object of the invention is to provide an improved circuit forstarting and operating an arc discharge device on direct current from analternating current supply that is readily adaptable to automaticstarting.

A more specific object of the invention is to provide an improvedcircuit for starting and operating an arc discharge device thatwilleliminate the necessity for employing a starting winding in thealternating/current transformer.

lt is still a further object of the invention to provide an improvedcircuitfor starting vand operating arr-arc discharge device on directcurrent from an alternating current supply that will employ smallersized starting capacitors.

ln accordance with the invention, the circuit includes a novelarrangementfof a powerstabilized transformer apparatus, a capacitorconnected in serieswith the secondary of the transformer, a filtercapacitor, a filter reactor, a starting capacitor and a means forinitiating the flow of an oscillatory current in aclosed loop comprisedof the filter capacitor, the filter reactor and the starting capacitorwhich form a lresonant circuit tuned to oscillate at a predeterminedfrequency. When the transformer is energized, the filter capacitor ischarged to a predetermined voltage.

In order to start the arc discharge device the oscillatoryV current isinitiated by connecting the filter reactor and starting capacitor acrossthe filter capacitor. The damped oscillation that follows in the tunedportion of the circuit provides an increased voltage at the lampterminals. During the operating condition of the circuit a directcurrent power output, which is not appreciably affected by normalvariations in the alternating current power supply, is supplied at thelamp terminals. Further, during the operating condition of the circuitthe lfilter capacitor and the inductive reactance, which also form apart of the oscillatory discharge circuit, function to filter thepulsating direct current output of the rectifier.

In another aspect of the invention a starting capacitor is used inconjunction with a reactor having a primary winding and a secondarywinding, the primary winding being in series circuit with the startingcapacitor and the secondary winding being in series circuit with arecti- Y fier output terminal and a lamp terminal.

A power stabilized transformer apparatus, as the term is used herein,includes a transformer and a serially connected capacitive reactancethat maintains a substantially constant power output in the secondarycircuit during normal fluctuations of the supply voltage and frcquency.A normal fluctuation in the supply voltage is considered to be plus orminus ten percent and avariation of plus or minus .2 `cycle per secondin the line frequency is considered to be normal. In thecircuit of theinvention, the secondary' of a transformer of comparatively high leakagereactance is connected serially with a first capacitor and with thefilter capacitor during a portion of the cycle to provide the requisitestabilizing elfect on the power output of the transformer.

The subject matter which we regard as our invention is set forth in theappended claims. The invention itself,

however, together with further objects and advantages thereof may bebetter understood by referring to the following description taken inconnection with the accompanying drawings in which:A

FIG. l is a schematic circuit diagram of the powerv FIG. 3 is aschematic circuit diagram of vanother em-v bodiment of the invention inwhich a sealed spark gap `is employed in conjunction with a seriallyconnected primary of a starting transformer;

FIG. 4 illustrates a curve of the instantaneous voltage at the lampterminals for the circuit shown in FIG. 3 during starting condition;

FIG. 5 illustrates the core and coil assembly of the transformer used inthe power stabilizing transformer apparatus of the circuits shown inFIGS. 1 and 3;

FIG, 6 shows the lamp watts versus line volts curves corresponding tothe circuit of lFIG. 1 for constant line frequencies of 60.2, 60.0 and59.8 cycles per second; and

FIG. 7 shows the lamp watts versus line frequency curves obtainedcorresponding to the circuit of FIG. 1 for constant line voltages of103.5, 115 and 126.5 volts.

Referring now to FIGS. 1 and 3, in accordance with the invention thecircuit which supplies a rectified direct current to a mercury vaporlamp 11 includes a transformer 12 having a primary winding 13 and asecondary winding 14. Although the invention will be described inconnection with the high pressure mercury vapor lamp 11, which in theherein described exemplification of the invention is a lamp of 100 wattsrating and designated commercially as UA-33, it is to be noted that theinvention is applicable to discharge lamps generally having a negativeresistance characteristic.

The high pressure mercury vapor lamp 11 is operated by an arc dischargebetween the electrodes (not shown). The starting voltage for the lampused in the exemplification of this invention is in excess of 700 voltsDC., while the normal operating voltage across the lamp is approximately100 volts D.C. The operating and starting circuit in accordance with theinvention must provide at the lamp terminals the required starting andoperating voltages from a readily available alternating current supplysource, for example, a 60 cycle, 115 volt A.C. supply. Although thecircuit of the invention is used in connection with a 115 volt A.C.supply, it will be appreciated that other supply voltages can be used inconnection with the circuit exemplifying the invention. In a commercialembodiment of the invention the transformer connections were designed sothat the transformer could readily be connected to a 115, 208 and 220volt A.C. power source.

A pair of terminals 15 and 16 connect the primary winding 13 of thetransformer 12 with a suitable power source (not shown). The transformer12 includes a magnetic core 17 and the shunt 1S, which are shownschematically in FIGS. 1 and 3. The magnetic shunt 13 provides the highleakage reactance necessary to limit the current flowing in thesecondary circuit and supplied to the lamp 11.

Although the secondary winding 14, as shown in FIGS. l and 3, isconnected with primary Winding 13 in isolated secondary relationship, itcan be readily seen that a secondary can be connected up in anautotransformer relationship so long as the necessary leakage reactancerequired for the current limiting effect and the requisite couplingbetween the primary 13 and secondary 14 for the power stabilizing effectis incorporated in the transformer design.

The secondary winding 14 is connected to one side of a capacitor 19. Theother side of the capacitor 19 is connected in circuit with a bridgerectifier 20. The bridge rectifier 20 includes four half-wave rectifyingelements 21, 22, 23 and 24, a pair of rectifier input terminals 25, 26and a pair of direct current output terminals 27, 23. The lamp 11 isconnected across the output terminals 27, 28 of the bridge rectifier 20by means of the terminal connections 29 and 30. f

Connected in series circuit between the bridge rectifier output terminal27 and the lamp `terminal connection 30 is a filter reactor or choke 31.During the starting condition of the circuit the filter choke 31functions as a reactor having a primary winding 32 and a secondarywinding 33, which includes the turns of the primary winding 32. Further,filter choke 31 furnishes the inductive reactance required in theoscillatory circuit which is ener- Cil gized by the filter capacitor 34connected across the bridge output terminals 27, 28.

As shown in FIG. l, a starting capacitor 35 is connected at one end to atap 36 at an intermediate point on the filter choke 31. As shown in FIG.3, the starting capacitor 35 is shown connected in series with a primarywinding 37. A shunting resistor 38 is provided across the startingcapacitor 35 for the purpose of draining otf the charge on the capacitor35 when the current to the starting circuit is cut off.

In the circuit illustrated in FIG. l, a momentary starting switch 39 isshown connected in series with the starting capacitor 35. The switch 39serves as a means for closing the oscillatory loop comprised of filtercapacitor 34, starting capacitor 35 and filter choke 31 during thestarting condition of the circuit.

It is to be noted that the circuit of the invention is readily adaptableto an automatic switching means, such as a sealed gap 43, as shown inFIG. 3, which provides the convenience of automatic starting. The sparkgap employed is of the low voltage type and breaks down when the filtercapacitor 34 charges to its predetermined voltage. Although a momentarystarting switch and a sealed gap are shown in the embodimentsillustrated in lFIGS. 1 and 3, respectively, it should be apparent thatother means for initiating the oscillatory current can be employed.

In FIG. 5 the arrangement ofthe core and coil assembly of thetransformer 12 is shown in more detail. A core structure 40 is comprisedof J-shaped laminations 41 stacked in alternate groups one-quarter of aninch thick to stagger the butt joints. The shunt 18 is made up of astack of rectangular laminations 42 of thin annealed magnetic materialand is disposed between the primary coil 13 and the secondary coil 14-so as to provide an air gap of .020 inch. In the illustrative example ofthe invention, for operation of the transformer 12 from a 60 cycle, 115volt alternating current supply, 252 turns of .0403 inch copper wirewere used in the primary coil 13 and 593 turns of .032 inch copper wirewere used in the secondary coil 14.

The transformer 12 functions in conjunction with the effectivecapacitance in the secondary circuit as a power stabilizing apparatus.In the illustrative example of the invention a suitable value of thecapacitance for the series capacitor 19 was determined experimentallyafter the value of the filter capacitance 34 was fixed by the filteringand starting requirements of the circuit. The determination was made byvarying the voltage and frequency supplied at the input terminals 15, 16of the transformer 12. and taking both voltage and ampere readings atthe lamp terminals 29, 30. In this manner, a value of capacitance wasselected that would provide a substantially constant power output at thelamp terminals 29, 30.

In the circuit shown in FIG. l, a capacitance of l0 microfarads for theseries capacitor 19, used in conjunction with the filter capacitor 34 of40 microfarads, was found to produce the desired stabilizing effect inthe power output. The curves for lamp watts versus line volts and linefrequency for the illustrative example of the circuit shown in FIG. 1are shown in FIGS. 6 and 7. In FIG. 6 the curves for line frequencies of60.2, 60.0 and 59.8 cycles per second are illustrated. FIG. 7 shows thelamp watts versus line frequency curves obtained when the line voitagewas held constant at 103.5, and 126.5 volts respectively. It can be seenfrom these curves that the power stabilizing transformer apparatusprovides the circuit with a substantially constant power supply. Thus,for the circuit shown in FIG. 1 a line voltage change from 103.5 voltsto 126.5 volts and a frequency change of 59.8 cycles per second to 60.2cycles per second results in maximum variation in wattage at the lampterminals of approximately 3.28 percent.

It is to be noted that during the starting or open circuit condition thepower stabilized transformer apparatus provides a root mean squarevoltage of approximately 215 volts at the rectifiedinput terminals 25,26. Duringthe normal operating condition of the lamp a root mean squarevoltage of approximately 85 volts is applied atthe rectifier inputterminals 25, 26.

An advantage in using a stabilized power transformer in the circuit ofthe invention over a constant voltage transformer of the prior art isthat the voltage supplied at the lamp input terminals can be regulatedWithout the use of a high resistance element in the transformer circuitwith its objectionable effect on the operating efficiency of the system.It will be appreciated that in accordance with the invention thealternating current voltage supplied to rectifier will vary as requiredby the lamp during warm up, and will maintain a substantiallyconstantpower supply at the lamp terminals 29, 39 within the normal range ofline voltage and frequency iiuctuations after the larnp4 has come up torated load. Accordingly, the circuit of the invention is particularlysuited for applications where a constant iiickerless light source isrequired.

The circuit shown in FG. l is operated by energizing the primary 13 ofthe transformer 12 while the starting switch 39 is in the open position.This is necessary in order that the filter capacitor 34 may be fullycharged. If the capacitor 34 is not fully charged before the startingswitch 39 is actuated, the peak voltage produced by the oscillatoryportion of the circuit may be insufficient to fire the lamp 11. In acommercial embodiment of the invention a relay was employed as amomentary switching means and was actuated with a delayed action toinsure that the switch (not shown) controlling the power supply to theprimary 13 and the starting switch 39 controlling the oscillatorycondition of the circuit were operated in proper sequence.

During one-half cycle of the applied alternating voltage when .the lamp11is operating, input terminal 26 becomes positive with respect to theterminal 25. Accordingly, the current from the transformer 12 enters therectifier at vterminal 26 and fiows through the rectifying element 23and outwardly at terminal 27 to the filter choke 31 and then to the lampterminal 30. On its return path the current enters the rectifier atterminal 28, is conducted through rectifying element 21, and leaves therectifier at terminal 25.

On the next half cycle when the polarity is reversed, the rectifyingelements 22 and 24 become the conducting elements. The current entersthe rectifier 20 at terminal and is conducted through the rectifyingelement 24, leaving the bridge rectifier 20 at terminal 27. On itsreturn path the current is conducted through the rectifying element 22and returns to the transformer secondary circuit by means of theterminal 26.

The full-wave rectifier bridge 20 functions in the usual manner tochange the single phase alternating current into pulses `ofunidirectional current utilizing both halves of the cycle, therectifiers21 and 23 handling one half of the cycle and the rectiers 22 and24 theother half of the cycle. The rectifying'elements used in theillustrative example ofthe invention were silicon rectifiers rated towithstand a peak inverse voltage of 400 volts. Silicon rectifiers wereused primarily because of their small size. Other types of rectifiersmay be used in the practice of' the invention.

During the normal operating condition ofthe circuit in accordance withVthe invention, the starting capacitor 3S of the-circuit shown in FIG. 1and the starting capacitor- 35 and the primary Winding 37 ofthe circuitshown in FIG. 3 are not eiective in the circuit. Thus, the filter choke31-and the filter capacitor 34 effectively function in the -f circuitto'convert the pulsating direct current output of the rectifier 20' intoa smooth direct current supply.

Itis to be noted that during arportion of a half cycle when theinstantaneous voltage of the filter capacitor 34 and the voltage acrossthe rectifier terminalsZS, 26 are approximately equal, the filterycapacitor 3,4, during this portion ofthe cycle, is receiving a currentflow and is in series circuit with the series capacitor 19. Inaccordance withV the present invention the filter capacitor 34 not onlyfunctions to filter the pulsating direct current but also appears in thesecondary circuit in conjunction with the series capacitor 19 to aid inproducing the stabilizing effect on the power output at the lampterminals 29,v 30. Further, itwill be appreciated that, in addition, thefilter capacitor 34 supplies energy to the starting network during theoscillatory startingperiod.

The Voltage at the output terminals 27, 28 of the bridge rectifier 2f?would be insufficient to start the lamp 11 in the circuit illustrated inFlGS. l and 3 if somemeans were not provided to step up the voltageduring the starting condition of the circuit. In accordance with theinvention, the additional voltage required for starting the mercury arclamp 11 is obtained by connecting the startingcapacitor 35 and thefilter reactor 31 across the charged filter capacitor 34, therebyinitiating the damped oscillatory RLC current. When the starting switch39 is closed in the circuit of FIG. 1`or when the sealed gap 43 of FIG.3 reaches its breakdown point, a damped oscillation occurs whichprovides a transient peak voltage suff ficient to start the lamp 11. Theexponential decay of the damped oscillation can be minimized veryreadily either by employing a low resistance winding in reactor 31 or bylusing a small starting capacitance 35 to achieve a high frequencyoscillation. Inthe circuit shown in FIG. l, it was found moreadvantageous to use the small startingrcapacitance 35.

FIGS.' 2 and 4 show the exponential decay voltage curves produced by thecircuits shown in FIGS. 1 and 3 respectively, during the startingcondition. It is to be noted that the voltage curve shown in FIG. 4 hasa peak voltage at the point of the cycle Where the abscissa has a zerovalue. Since the exponential curve has a negative decrement, a maximumpeak Voltage is available to start the lamp.

It can be seen from curves of FIGS. 2 and 4 that dulring the startingcondition approximately twice the voltage ofthe predetermined constantvalue to which the filter capacitor 34 is charged appears at the lampterminals 29, 30. An advantage in using the transformer type ofconnections `shown in FIGS. 1 and 3 is that the instantaneous voltageincrement contributedby the oscillatory portion Of the circuit variesdirectly with the number of turns in the. secondary and inversely withthe num-ber of turns in thev primary. Itwili be noted that the number ofturns of kthe Vreactor secondary winding is limited in View of the dualfunctionof the component as a filter choke during the operatingcondition ofthe circuit and as the inductive reactance of an oscillatorydischarge circuit during the starting condition. l

In the exemplification of the invention as shown in FIG. 1, theVinductive reactance of the primary and secondary windings ,32, 33 Vwerefirst determined experimentally by selecting values that'provided theoptimum filtering action in combination with the filter capacitor 34 forthe 100 watt mercury `vapor'lamp 11 and then determining the number ofturns that would provide sufiicient starting voltage. It was found thata choke coil having an inductance of 2.12 henries and 1207 turns of.0285 inch coppernwire andY placing the tap 36 at a point .on the coiltoprovide. 402 turns for the primary 32 gavesatisfactory resultsfor bothstarting and operating conditions of the circuit. Y

The circuit of FIG. l has the advantage that a standard choke .coil canbe used. It is to be noted that turns of extremely fine wire cannot beused in the filter choke 31,.of the. circuit `shown in FIG. 1 since anincreased resistance resultsin an increased negative decrement, whichVmight result in unreliable starting. Since the maximum voltage, asshown-in the curve of FIG. 2 does not occur at the point wheretheabscis'sa .has Vazerovalue, in-v creased resistance of the filter choke31 has the effect of reducing the instantaneous peak voltage used tostart the lamp.

This difficulty is overcome in the circuit shown in FIG. 3 by connectingthe primary and the secondary windings so that the current flow to theprimary and secondaries are in opposite directions. Having reference nowto the instantaneous voltage curve shown in FIG. 4, it will be notedthat all the instantaneous values of the peak voltages are positive invalue and the maximum peak voltage occurs when the value of the abscissais zero. Accordingly, in this circuit fine copper wire can be employedin the primary winding with a resultant saving of copper.

The illustrated values of circuit components referred to herein are usedto exemplify an embodiment of the applicants invention. It is to beunderstood, however, that the particular mercury vapor lamp and thespecic values of the circuit components are given by way ofillustration. In general, the invention is applicable to direct currentdischarge lamps having a negative resistance characteristic andrequiring a starting voltage that is much greater than that used duringnormal operation of the lamp.

It will be appreciated that various sizes and types of direct currentlamps and other modifications in circuit details, such as thearrangement of the transformer means or the rectifying means or in thefilter choke will readily occur to those skilled in the art. While wehave described above a particular embodiment of the invention, manymodifications may be made. It is to be understood, therefore, that weintend by the appended claims to cover all such modifications that fallwithin the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

l. A circuit for starting and operating an arc discharge device ondirect current from a source of alternating current comprising a pair ofalternating current input terminals, a power stabilized transformerincluding a primary winding, a secondary winding and a seriallyconnected capacitor, said primary being connected in circuit with saidinput terminals, a rectifying means having a pair of input terminals anda pair of direct current output terminals, said input terminals beingconnected in circuit with said secondary, a filter capacitor connectedacross said direct current output terminals, a pair of lamp terminalconnections; an oscillatory circuit comprising a starting capacitor andan inductive reactance connected in series circuit relationship, saidstarting capacitor and inductive reactance being connected in circuitwith said filter capacitor and said lamp terminal connections, means forclosing said oscillatory circuit to initiate the oscillatory current,said filter capacitor being initially charged and supplying energy tosaid oscillatory circuit, said oscillatory circuit providing a transientvoltage sutiicient to start said arc discharge device, said means forclosing said oscillator circuit being connected in series circuitrelationship with said starting capacitor, and said filter capacitor andsaid inductive reactance filtering the pulsating current output of saiddirect current output terminals after said arc discharge device isstarted.

2. A circuit for starting and operating an arc discharge device ondirect current from a source of alternating current comprising a pair ofalternating current input terminals, transformer means having a primaryand a secondary, said primary being connected across said inputterminals, said transformer means having suiiicient reactance forballasting said arc discharge device during operation, a first capacitorconnected in series circuit with said secondary, rectifying meansincluding a pair of direct current output terminals and a pair ofrectifier input terminals connected in circuit with said first capacitorand said secondary, a second capacitor connected across said directcurrent output terminals, a third capacitor connected in circuit withsaid second capacitor, a reactance means connected in series circuitrelationship with said 8. third capacitor and comprising therewith anoscillatory circuit, means for closing said oscillatory circuit toinitiate the oscillatory current, said second capacitor being initiallycharged and supplying energy to said oscillatory circuit, saidoscillatory circuit providing a transient voltage superimposed upon thevoltage of said second capacitor sufficient to start said dischargedevice, said means for closing said oscillatory circuit being connectedin series circuit with said third capactor, and said reactance means andsaid second capacitor filtering the pulsating direct current output ofsaid direct current output terminals after said discharge device isstarted.

3. A circuit for starting and operating an arc discharge device fromdirect current from a source of alternating current comprising a pair ofalternating current input terminals, a high leakage reactancetransformer having a primary winding and a secondary Winding, saidprimary winding being connected across said alternating current inputterminals, rectifying means having a pair of rectifier input terminalsand a pair of direct current output terminals, said rectier inputterminals being connected in circuit with said secondary winding, afirst capacitor connected in series circuit with said secondary windingand one of said rectifier input terminals, a second capacitor connectedacross said direct current output terminals, a pair of lamp terminalconnections, a filter choke connected in series circuit with one of saiddirect current output terminals and one of said lamp terminalconnections and having a tap located at an intermediate point on saidfilter choke, a third capacitor, a switching means, and circuit meansconnecting said tap, said third capacitor and said switching means inseries circuit across said lamp terminal connections, said filter chokeand said third capacitor being connected in series circuit relationshipand comprising a portion of an oscillatory circuit, said switching meanscausing said second capacitor to supply energy to said oscillatorycircuit to provide a voltage sufficient to start said discharge deviceand remaining open after said arc discharge device has started, saidfilter choke and said second capacitor filtering the pulsating directcurrent output of the direct current output terminals of said rectifyingmeans after said discharge device is started.

4. The circuit for starting and operating an arc discharge device ondirect current from a source of alternating current comprising a pair ofalternating current input terminals, a pair of lamp terminalconnections, a transformer means having a primary and a secondary, afirst capacitor connected in series with said secondary, rectifyingmeans having a pair of rectifier input terminals and a pair of directcurrent output terminals, said rectifier input terminals being connectedin circuit with said secondary and said I'irst capacitor, a secondcapacitor connected across said direct current output terminals, aninductive reactance means having a primary winding and a secondarywinding, said secondary winding of said inductive reactance means beingconnected in series circuit between one of said lamp terminalconnections and one of said direct current output terminals, a thirdcapacitor connected in series circuit relationship with said secondarywinding, said third capacitor and said reactance means comprising anoscillatory circuit, means for con necting said oscillatory circuitacross said second capacitor, said means including a switch connected inseries with said third capacitor and causing said second capacitor tosupply energy to said oscillatory circuit and provide a transientvoltage at said lamp terminal connections superimposed upon the voltageacross said sec- 0nd capacitor sufcient to start said arc dischargedevice, said switch remaining open after said discharge device hasstarted said inductive reactance means and said second capacitorfiltering the pulsating direct current output of said direct currentoutput terminals after said discharge device is started.

5. A circuit for starting and operating an arc discharge device ondirect current from a source of alternating current comprising a pair ofalternating current input terminals, a high reactance transformer havinga primary winding and a secondary Winding, said primary winding beingconnected across said input terminals, a first capacitor connected inseries with said secondary winding, a bridge rectifier having a pair ofinput terminals and a pair or direct current output terminals, saidrectifier input terminals being connected in circuit with said firstcapacitor and said secondary Winding, a second capacitor connectedacross said direct current output terminals, a pair of lamp terminalconnections, an inductive reactance connected in circuit with one ofsaid lamp terminal connections and one of said direct current outputterminals, a third capacitor connected in series circuit relationshipwith said inductive reactance, a filter circuit comprising said secondcapacitor and said inductive reactance ltering the pulsating directcurrent output of said direct current output terminals after said arcdischarge device is started, an oscillatory circuit comprising saidthird capacitor and said inductive reactance, switching means connectedin series circuit relationship with said third capacitor and causingsaid second capacitor to supply energy to said oscillatory cirfcuit inorder to provide at said lamp terminal connections a transient voltagesuperimposed upon the voltage across said second capacitor suflicient tostart said .arc discharge device.

6. A circuit for starting and operating an arc discharge device ondirect current from a source of alternating current comprising a pair ofalternating current input terminals, a high reactance transformer havinga primary Winding and a secondary winding, said primary winding beingconnected across said input terminals, a first capacitor connected inseries circuit with said secondary winding, a bridge rectier having apair of input terminals and a pair of direct current output terminals,said input terminals being connected in circuit with said firstcapacitor and said secondary winding, a second capacitor connectedacross said direct current output terminals, a pair of lamp terminalconnections, an inductive reactance means having a primary winding and asecondary Winding, said secondary winding of said inductive reactancemeans being connected in circuit with one of said terminal lampconnections and one of said direct current output terminals, a thirdcapacitor connected in series circuit relationship with said primarywinding of said inductive reactance means and comprising therewith anoscillatory circuit, and a switching means connected in series circuitrelationship with said third capacitor for causing said second capacitorto supply energy to said oscillatory circuit to provide a transientvoltage suiiicient to start said arc discharge device, said secondcapacitor Iand said inductive reactance means filtering said pulsatingdirect current output of said direct current terminals after said arcdischarge device is started.

7. A :circuit for starting and operating an arc discharge device ondirect current from a source of alternating current comprising a pair ofalternating current input terminals, a first transformer having aprimary winding and a secondary winding, a first capacitor connected inseries circuit with said secondary winding, a bridge rectifier having apair of rectifier input terminals and a pair of direct current outputterminals, said input terminals being connected in circuit with saidsecondary winding and said first capacitor, a second capacitor connectedacross said direct current output terminals, a pair of lamp terminalconnections, `an inductive reactance connected in circuit with yone ofsaid lamp terminal connections and one of said direct current outputterminals, a third capacitor, a sealed gap means, said third capacitorand said sealed gap being serially connected in circuit `across saidlamp terminal connections, said inductive reactance and said thirdcapacitor being connected in series circuit relationship and comprisingan oscillatory circuit, said sealed gap causing said second capacitor toexcite said oscillatory circuit in order to provide a transient voltagesufficient to start said arc discharge device, and said inductivereactance and said second capacitor filtering the pulsating directcurrent `output of said direct current output terminals after said arcdischarge device is started.

8. A circuit for starting and operating an arc discharge device ondirect current from a source of alternating eurrent comprising a pair ofalternating current input terminals, a high reactance transformer havinga primary winding and a secondary winding, said primary winding beingconnected across said alternating current input terminals, said bridgerectitier input terminals being connected in circuit with said firstcapacitor and said secondary Winding, a second capacitor connectedacross said direct current output terminals, a pair of lamp terminalconnections, a filter choke having a tap at an intermediate point andconnected in series circuit between one of said lamp .terminalconnections and one of said direct current output terminals, a thirdcapacitor, a momentary switch, said third capacitor and said momentaryswitch being connected in series circuit with said tap across said lampterminal connections, said third capacitor and the portion of saidfilter choke between said tap and one of said direct current outputterminals being in series circuit relationship and comprising anoscillatory circuit and said momentary switch when actuated causing saidsecond capacitor to excite said oscillatory circuit to provide atransient voltage superimposed upon the voltage across said secondcapacitor sufficient to start said arc discharge device, said momentaryswitch remaining open after said arc discharge device has started, saidfilter choke and said second capacitor filtering said pulsating directcurrent output of said direct current output terminals after said arcdischarge device is started.

9. A circuit for starting and operating an arc discharge device ondirect current from a source of alternating current comprising a pair ofalternating current input terminals, a high leakage reactancetransformer having a primary winding and a secondary winding, saidprimary winding being connected across said input terminals, a firstcapacitor connected in series circuit with said secondary winding, abridge rectifier having a pair of rectifier input terminals and a pairof direct current output terminals, said bridge rectitier inputterminals lbeing connected in circuit with said first capacitor and saidsecondary winding, a `second capacitor connected across said directcurrent output terminals, a pair of lamp terminal connections, aninductive reactance means having a primary winding and a secondarywinding connected in circuit between one of said lamp terminalconnectionsand one of said direct current output terminals, a thirdcapacitor, said third capacitor and said inductive reactance meanscomprising an oscillatory circuit and a sealed gap, said sealed gap andsaid third capacitor being connected in series circuit with said primaryof said inductive reactance means and across said lamp terminalconnections, said sealed gap causing said second capacitor to excitesaid oscillatory circuit to provide a transient voltage `across saidlamp terminal connections sufficient to start said arc discharge device,said secondary winding and said second capacitor filtering saidpulsating direct current output of said direct current output terminalsafter said discharge device is started.

References Cited in the file of this patent UNITED STATES PATENTS'2,717,335 Sims et al Sept. 6, 1955 2,717,337 Laird Sept. 6, 19552,737,612 sims Mar. 6, 1956 2,757,318 Noel et al. July 3l, 1956 FOREIGNPATENTS 618,256 Great Britain Feb. 18, 1949

